1. Field of the Invention
The present invention relates to control valves for controlling the flow rate and pressure of a fluid. More particularly, the present invention relates to a control valve, constructed as a packer valve, adapted to control the direction and regulate the flow rate and pressure of a fluid flowing in a conduit, such as a well bore.
2. Description of the Prior Art
Inflatable packers for directing fluid flow in a fluid conduit are well known in the art. Typically, such inflatable packers are utilized in downhole applications for sealing a well bore (e.g., oil well or water well). As an example, a pair of such packers can be used in the testing of a drilled well formation by isolating a length of the formation in communication with a testing flow port.
In general, this type of packer includes an inflatable packer element which can be inflated to sealingly engage the inside diameter of the well bore. Fluid pressure for inflating the inflatable packer element is typically introduced through an operating string placed into the well bore, or by a separate pneumatic or hydraulic hose adjacent and external to the operating string. Such inflatable packers may also include some means for locking the inflatable packer element in an inflated or sealing condition. Packers can be a "multi-set packer" which can be deflated and re-inflated within a well bore, or a "single set packer" adapted for a single downhole inflation.
In the past, such inflatable packers have been constructed to either prevent or to permit fluid flow. Inflatable packers are thus not adapted to selectively regulate a fluid flow rate within a well bore.
It is often desirable to regulate the fluid flow rate or fluid pressures of fluids injected into or pumped out of a well. Recharge water wells, for instance, may be utilized in Aquifer Storage and Recovery (ASR) programs to assist communities during times when water demand peaks. The (ASR) process involves storing treated drinking water in suitable underground aquifers through recharge wells during low-demand months and recovering the water through the same wells during high demand months.
With such recharge wells, treated water is injected into the wells for storage. This injection is typically accomplished at a predetermined flow rate and pressure. Flow and pressure regulation is typically achieved utilizing a surface mounted flow control valve.
A variety of flow control valves are well known in the art for controlling fluid flow within a conduit. As an example, globe control valves are often utilized in high flow applications. Such control valves may include a spring actuated, tapered, sealing member that operates in conjunction with a contoured orifice. The location of the sealing member with respect to the orifice can be adjusted to provide a cross section which achieves a desired fluid flow rate and frictional pressure loss.
A problem with such flow control valves is that they cannot regulate a wide range of flows with the large pressure drops inherent in their design. Further, their size is such that they cannot fit in a well and allow pumping. Moreover, these control valves have a limited operating range because typically, a single sealing member and contoured orifice are utilized to achieve a large pressure drop. Control is difficult because only a small linear movement of the sealing member relative to the contoured orifice is required. In addition, with a single orifice valve, fluid flow velocities through the control valve are relatively large. Such high flow velocities produce hydrodynamic noise and promote cavitation within the control valve. Finally, a shortcoming of such prior art control valves is that because of their sensitivity, they are difficult to utilize with a fluid containing a particulate material (e.g., dirty water).
The present invention recognizes that a packer valve may be constructed as a control valve to direct fluid flow within a conduit and also to regulate fluid pressures and flow rates within the conduit. Moreover, such a packer valve can be constructed to achieve an infinitely variable frictional pressure loss for a fluid flowing through the packer valve. Further, such a packer valve can be constructed to achieve a high flow rate with a low fluid velocity through the valve. Still further, such a valve can be made of a size which permits it to be placed into a well.
Accordingly, it is an object of the present invention to provide a packer valve adapted to direct fluid flow within a fluid conduit such as a well.
It is another object of the present invention to provide such a packer valve that can be placed downhole in a well bore and controllable from the surface.
It is a further object of the present invention to provide such a packer valve in which fluid velocities through the valve are low and frictional pressure losses through the valve are infinitely variable to control fluid flow over a wide range of pressures whether down hole in a well or for such control in surface piping systems.
It is yet another object of the present invention to provide such a packer valve that can be used with a variety of fluids including a fluid having particulate material therein.
It is a further object of the present invention to provide a packer valve especially adapted for controlling the flow rate and pressure of a fluid injected into a well.
It is yet another object of the present invention to provide a packer valve suitable for high flow and high pressure applications that is simple and reliable.
It is yet another object of the present invention to provide a packer valve suitable to retrofit existing wells for pumping and injection.